Re: [PATCH net v2 2/3] net: phy: smsc: Force predictable MDI-X state on LAN87xx

[Maxime Chevallier <maxime.chevallier@bootlin.com>]

On Thu,  3 Jul 2025 13:49:40 +0200
Oleksij Rempel <o.rempel@pengutronix.de> wrote:

> Override the hardware strap configuration for MDI-X mode to ensure a
> predictable initial state for the driver. The initial mode of the LAN87xx
> PHY is determined by the AUTOMDIX_EN strap pin, but the driver has no
> documented way to read its latched status.
> 
> This unpredictability means the driver cannot know if the PHY has
> initialized with Auto-MDIX enabled or disabled, preventing it from
> providing a reliable interface to the user.
> 
> This patch introduces a `config_init` hook that forces the PHY into a
> known state by explicitly enabling Auto-MDIX.
> 
> Fixes: 05b35e7eb9a1 ("smsc95xx: add phylib support")
> Signed-off-by: Oleksij Rempel <o.rempel@pengutronix.de>
> Cc: Andre Edich <andre.edich@microchip.com>

The patch looks good to me, but I have a few questions.  As this
overrides some configuration on existing HW, and I'm not utra familiar
with auto-mdix, is there any chance this could cause regressions ?

Especially regarding your patch 3, is there any chance that the PHY is
strapped in a fixed MDIX mode to address the broken autoneg off mode ? 

I'm not saying that strapping is a good solution for that ofc :) it's a
shame we can't read the strap config :/

Maxime